I'm used to RyanAir so I feel like Frontier will be the same deal. With RyanAir if you show up at the airport without everything in order, you pay.

So this may be a dumb question but I can't get a clear answer on the Frontier website.

I have the Frontier Android App and it lets me check in. It's given me something that looks like a boarding pass with a QR Code.

Is that enough to get on the plane, or do I need a physical piece of paper? I'm guessing checking in at the airport will involve $$$

The Frontier site doesn't really mention e-boarding passes, and just mentions paper.

Also I'm not up for risking my backpack, so I'm taking a supermarket cotton bag as my personal item hehe